Nylon has been widely used in engineering plastics due to its high strength, high wearing resistance, high chemical resistance, and good deformation resistance and anti-aging ability. Nylon synthesized by anionic ring-opening polymerization has a much higher molecular weight than that of nylon synthesized by condensation polymerization, thus it is superior in applicability.
Nylon particles see a great potential for application in coatings and raw materials for rollforming molding and extrusion molding. Conventional processes for preparing nylon particles include solution precipitation, emulsion, direct polymerization, mechanical ground (low temperature, slicing process and air flow crush), and the like. These processes, however, typically suffer from such drawbacks as technical complexity, high cost and high energy consumption, irregular powder shape, large particle size and wide distribution of particle size, rendering significant difficulty in their practical application.
It is disclosed in European Patent No. EP1636292 that polyamide spherical particles were made by emulsion polymerization. It is disclosed in WO 03097228 that polyamide spherical particles were made by interfacial polycondensation. However, these two processes are not suitable for industrial application for their process complexity and the need of a great deal of solvent and dispersant.
A method is disclosed in Chinese Patent No. CN1624025 wherein a polyamide powder was obtained by mixing polyamide granules and a water soluble polymer to give a co-blend with polyamide as the dispersed phase and the water soluble polymer as the continuous phase, and then removing the water soluble polymer with water. While this method is desirable in industrialized manufacture, the preparation of polyamide powder used as the raw material requires consumption of a lot of energy.